Nik Wallenda performs a walk on a tightrope with the Skylon Tower in the background during training in Niagara Falls, N.Y., Tuesday, May 22, 2012. Wallenda can't visit a new place without envisioning a wire strung high above his head: Linking buildings,landmarks, nations. Even as a 6-year-old at Niagara Falls with his parents, he pictured walking a tightrope over the raging, whitewater maw. Now 33, he's ready to live out that childhood fantasy when he attempts Friday, June 15, 2012 to become the first p